This application relates to the digital image processing arts. More particularly, it relates to a method and apparatus for directly processing compressed digital image data of a base image for purposes of automatically locating a paste location in the compressed data without decompressing or even partially decompressing the data. This allows a separate, secondary compressed digital image to be electronically pasted directly into the identified paste location without decompression of either image. The present invention is described with particular reference to digital image processing of documents or images which have been compressed according to the Joint Photographic Expert Group (JPEG) recommendation ISO DIS 10918-1 which has become an international standard for lossy compression of still images. However, those of ordinary skill in the art will recognize that the invention has wider application and is not meant to be limited for use with any particular compression standard. The terms digital "image" or "document" as used herein may refer to a digital representation of text, a photograph or other picture, continuous tone (i.e., "contone") data, halftone data, or any other digital image data.
A common problem encountered in assembling or reproducing a final, printed document is the need to include a photograph or other image at a select location on a page of text or other information. Using a manual approach, one might simply physically paste the actual photograph or other secondary image directly to the printed base document page using tape or glue. This combined page is then reproduced. Of course, such an approach is time consuming, and not practicable for large documents which must be fed into an automatic document feeder (ADF) for purposes of making multiple copies of same.
Another approach using digital image reproduction apparatus has been to scan the base document, scan the photograph or other secondary document which is to be inserted into the base document, decompress the scanned base document data (i.e., the base image data), display the base image data on a visual display, and allow a user to command the reproduction apparatus to paste the secondary image data electronically into the desired location of the decompressed base image data. For binary or so-called black-and-white digital image reproduction apparatus, this latter approach may be somewhat acceptable given that decompression of monochromatic data is not unduly time consuming or otherwise performance-intensive. For example, an ordinary page of decompressed black-and-white image data may require only approximately 1 megabyte (MB) of decompressed data which is not so large to inhibit display and processing the decompressed data as described to accomplish the pasting operation. Of course, a certain amount of user intervention is still required which can reduce document reproduction efficiency.
On the other hand, digital reproduction of color documents requires enormous amounts of data. For example, a typical color document may require approximately 30 MB-90 MB of decompressed digital image data or more for its reproduction. Obviously, it is not feasible and/or desirable to decompress this data as needed for display and other processing to effect the desired pasting operation. The decompression and other processing of such large amounts of data would slow the entire document reproduction process to an unacceptable level for practical application.
Accordingly, in light of these deficiencies and others associated with known digital image processing apparatus and methods, it has been deemed desirable to develop a method and apparatus which simplifies the insertion of a secondary digital image such as a digital image of a photograph or the like into digital image data derived from a base document without requiring the base document image data to be decompressed for purposes of locating the appropriate paste location or to perform the actual electronic pasting operation.